Impeller for a submerged centrifugal fuel pump



Sept. 1, 1970 D. R. COMPTON 3,526,465

IMPELLER FOR A SUBMERGED CENTRIFUGAL FUEL PUMP Filed Sept. 10, 1968 34 I 2o \v 44 3 FIG. 3

INVENTOR DQNALD R. CQMPTON 7 ATTORNEY United "States Patent O "ice U.S. Cl. 415-198 3 Claims ABSTRACT OF THE DISCLOSURE A centrifugal fuel pump impeller mounted on the shaft of an electric motor includes a circular plate having on its intake side a series of ridges running from inner points of the plate to its periphery to form pumping vanes. The trailing sides only of the ridges have fillets along their entire length to prevent vapor lock. On the other side of the plate there is an annular ridge and short vanes between it and the periphery of the plate for preventing pumped fuel from flowing inwardly over the top of the impeller. The chamber in which the impeller is located has a clearance space for the air and vapor in the fuel to escape over the top of the impeller.

BACKGROUND OF THE INVENTION The invention relates particularly to a fuel pump adapted to be submerged in the gasoline tank of an automobile. A serious fault of prior centrifugal pumps of this type is the occurrence of vapor lock. Vaporization in the tank takes place since the temperature of the fuel may rise as much as 20 above ambient under summertime driving conditions. A major source of heat is the air blown back by the radiator fan, and the mufiler and the tail pipe may be located so that they radiate heat to the fuel tank. Since gasoline is made up of a number of hydrocarbons, some of which boil at temperatures below 100 F., vaporization occurs readily. Observation of a prior art centrifugal fuel pump, equipped with a transparent cover plate and operated while the fuel was being raised in temperature, revealed that a vapor bubble formed on the trailing side of the impeller vanes, and as the temperature increased the vapor bubble became larger and larger until the pump ceased pumping. The exact mechanism of vapor bubble formation was not determined, but it is believed that some vaporization occurs due to agitation by the impeller vanes, and in addition there is created .behind the vanes a zone of reduced pressure which probably promotes vaporization. With the impeller of this invention, having fillets on the trailing sides of the vanes, it 'was found that vapor lock does not occur under the same test conditions as those which caused vapor lock with the prior art impeller which was tested.

SUMMARY OF THE INVENTION A fuel pump adapted to be mounted in the gasoline tank of an automobile has a centrifugal impeller mounted on a shaft of an electric motor. The impeller is located in an intake and pumping chamber which provides clearance space round the impeller in which vapor may pass round and over the impeller and escape. The impeller has a plate provided with vanes on the bottom thereof. The vanes are in the form of arcuate ridges extending radially outward. The trailing sides of the vanes have fillets sloping from the tops of the vanes or ridges down to the plate. The fillets prevent the formation of vapor bubbles behind the vanes, probably because they prevent or reduce cavitation behind the vanes. On the top side, the impeller plate has an annular ridge rather close to the periphery and short vanes extending from the annular 3,526,465 Patented Sept. 1, 1970 ridge to the periphery, for the purpose of obstructing or preventing the flow of liquid fuel over the top of the impeller. The vanes on the top side of the impeller do not have fillets and, therefore, these vanes may produce regions of reduced pressure on the top side of the impeller, in which region vapor may collect, and then escape through an opening above the impeller.

BRIEF DESCRIPTION OF THE DRAWING One embodiment of the invention is illustrated in the accompanying drawing having the following figures.

FIG. 1 is a top plan view of the impeller.

FIG. 2 is a bottom plan view of the impeller.

FIG. 3 is a partial sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is a sectional view of the lower portion of the pump.

DESCRIPTION OF THE PREFERRED "EMBODIMENT The invention relates to an improved impeller particularly for the electric motor driven centrifugal fuel pump disclosed in copending application of Charles W. Jeep, Jr. and Rooney W. Davis for Centrifugal Pump for a Fuel Tank, Ser. No. 756,643 filed Aug. 30, 1968, now Pat. 3,507,582 designed to be mounted on the bottom of a fuel tank of an automobile. The structure of the entire pump is shown and described in the aforementioned application, the disclosure of which is incorporated herein by reference. The pump has a plastic casing 10, only the lower portion of which is shown in FIG. 4, with an inlet 12. A shaft 14 of an electric motor (not shown) extends through a partitioning member 16 into a pumping chamber 18. Impeller 20 is mounted on the end of shaft 14. Fuel enters chamber 18 through perforated metallic plate 22 supported on lugs 24 of inlet 12. Chamber 18 has an outer wall 19 having a liquid fuel outlet (not shown) communicating with fuel delivery passage 26. Chamber 18 provides a sufiicient clearance space around impeller 20 to permit air and vapor in the fuel to pass round the impeller, through opening 28 in partition 30 and thence into passage 32, which returns the vapor to the fuel tank.

Impeller 20 has a hub 34 fastened to motor shaft 14. Plate 36 extends outwardly from hub 34. A series of arcuate vanes 38 extends outwardly fromthe hub to the periphery of plate 36 on the bottom thereof. The forward edge 40 of each vane is perpendicular to plate 36, while the trailing side 42 is provided with a fillet which is included to plate 36. On the upper side of plate 36 is an annular ridge 44 and a series of short vanes 46 extending from annular ridge 44 to the periphery of plate 36.

In operation, vanes 38 on the bottom side of impeller 20 impart a centrifugal motion to the liquid fuel in chamber 18 supplied through inlet 12 and perforated plate 22. The fuel, which is circulated and urged against the wall 19 of chamber 18, passes through an opening in wall 19 communicating with passage 26. The fuel is prevented from passing over the top of impeller 20 by short vanes 46, as well as ridge 44. Vapor, however, in chamber 18 will rise and move through the clearance space between impeller 20 and wall 19 to the top side of the impeller, and eventually will rise through opening 28 and passage 32, and thus return to the fuel tank. Movement of liquid fuel over the top side of the impeller is obstructed by ridge 44. The formation and growth of vapor bubbles, which were found to occur near the trailing edge of the vanes on the bottom side of prior art impellers, do not take place. In the prior art pumps vapor bubbles grew in size until the pumping action practically disappeared, that is, until vapor lock developed. It

is believed the present impeller is free from vapor lock because fillets 42 behind vanes 38 substantially eliminate cavitation behind the vanes, and so do not promote the accumulation of vapor behind the vanes. In any event, tests have demonstrated that vapor lock does not occur when using the present impeller.

I claim: 1. A centrifugal liquid fuel pump for an internal combustion engine having an impeller, a vertical rotary motor shaft, and a housing having a chamber having a fuel inlet in the bottom thereof and a gas outlet in the top thereof, said impeller having a hub fixed to said shaft, a generally fiat plate of substantially uniform thickness having a circular perimeter extending outwardly from said hub, a plurality of vanes on the bottom side of the plate in the form of arcuate ridges extending from the hub to the periphery of said plate, the trailing sides only of the vanes having fillets forming inclined surfaces extending from the tops of the vanes to the plate for reducing cavitation behind the vanes and thereby preventing vapor lock, and a closed annular ridge on the top side of said plate outwardly of said gas outlet for impeding inward radial flow of liquid fuel on said top side of said plate.

2. A centrifugal fuel pump according to claim 1, wherein said annular ridge is located relatively near the periphery of said plate and a plurality of vanes extend from said annular ridge to the periphery of the plate.

3. A centrifugal fuel pump according to claim 2, in which the vanes on both sides of the impeller have a uniform height. 7

References Cited UNITED STATES PATENTS 890,662 6/1908 Lager 1031 15 1,003,020 9/1911 Webb 103-115 2,127,865 8/1938 Goddard 1031 15 2,791,183 6/1957 Ygge 103--115 2,822,145 2/1958 McLean 103--115 3,040,670 6/ 1962 Schenc-k et a1. 103111 3,295,456 1/1967 Warren 1031 15 HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 55-400 

